Getting started with Apache ZooKeeper

1. ZooKeeper In Action
Juven Xu (许晓斌)

2. •
Apache ZooKeeper is an effort to develop and
maintain an open-source server which enables
highly reliable distributed coordination.

3. Requirements
•
JDK 1.6 & JAVA_HOME
•
Maven (we will need to write some java code)

4. Installation
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Download: http://zookeeper.apache.org/
releases.html
•
mv conf/zoo_sample.cfg conf/zoo.cfg
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edit zoo.cfg: dataDir=/my/zk/dataDir
•
bin/zkServer.sh start

5. ZooKeeper Data Tree

6. ZooKeeper API

7. bin/zkCli.sh
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zkCli.sh -server localhost:2181

8. Exercise #1
•
install zookeeper, start it, and create a znode /test/
node1 with value “hello-world”

9. Problem with Polling

10. ZooKeeper Watch

11. Coding for Watch

12. Coding for Watch

13. Exercise #2
•
Write your own watch, print new value on each time
znode /test/znode1 changes

14. ZooKeeper Ensemble

15. To Setup an Ensemble
•
conf/zoo.cfg: //on all servers
server.1=10.20.157.1:2888:3888
server.2=10.20.157.2:2888:3888
server.3=10.20.157.3:2888:3888
•
conf/zoo.cfg: //this location is important
dataDir=/home/admin/zookeeper/zkData
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echo 1 > ${dataDir}/myid //on server.1
echo 2 > ${dataDir}/myid //on server.2
echo 3 > ${dataDir}/myid //on server.3

16. To Setup an Ensemble
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If you want to set up ensemble on one machine,
make sure these values are different:
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dataDir
•
clientPort
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the ports of server.{1-5}

17. Client of a Ensemble

18. Exercise #3
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Find 2 friends, set up an Ensemble with them.
•
Update your client, registering all the 3 servers.
•
Kill one server, see if ensemble and client still
works
•
Kill another server (now only one left), see how it
goes.